The relationship of plasma estradiol and progesterone levels to fatty liver-hemorrhagic syndrome (FLHS) was studied with three groups of 9 White Leghorn hens per group. One group was fed ad libitum the other two group were force-fed at 120% and 135% of their own pre-experimental daily feed intake. Force-feeding for 3 weeks produced FLHS. The average FLHS score was 1.6 for control, 3.7 for 120% force-fed, and 4.5 for 135% force-fed. The average liver fat contents were 31.3%, 75.1%, and 76.8% (dry matter basis), respectively. Plasma estradiol averaged 165 pg/ml in the control group and 194 and 247 pg/ml in groups force-fed at 120% and 135%, respectively. The correlation coefficient between plasma estradiol and FLHS was .72 (P less than .01). No significant differences in plasma progesterone were obtained among the control and force-fed groups. The data indicate that high endogenous estrogen levels are associated with FLHS.